The Mixed-member proportional representation (MMP) is a voting system used in several countries, including New Zealand, Germany, and Lesotho. It is a mixed electoral system in which voters cast two votes: one for a candidate in their single-seat constituency and one for a political party. The party vote is used to allocate additional members to produce or deepen overall proportional representation. The key features of the MMP voting system are:

• Two votes: Under MMP, voters get two votes: one to decide the representative for their single-seat constituency, and one for a political party.

• Proportional representation: The nationwide seats are allocated to political parties in a compensatory manner to achieve proportional election results. This means that two parties that each receive 25% of the votes end up with about 25% of the seats, even if one party wins more constituency seats than the other.

• District seats and PR seats: The system has district seats and proportional representation (PR) seats. The district seats are filled by the candidate who gets the most votes in their constituency, while the PR seats are awarded to compensate for any disproportionality produced by the district seat results.

• Minimum threshold: Political parties must get at least 5% of the party vote or win an electorate seat before they can have any seats in Parliament.

MMP is designed to produce proportional results, but it is possible that the disproportionality in the single-member district results is so great that the list seats cannot fully compensate for it. In such cases, proportionality can be closely approached if the size of the legislature is slightly increased.